Automatic bag selector and opener



Feb. 18, 1958 v. A. LEHMKUHLE ETAL 2 AUTOMATIC BAG SELECTOR AND QPENER 2 Sheets-Sheet 1 Filed April 11. 1955 INVENTORS lQ/ChQl'd 6. Oros Fly. /4 V/ry/I ,4. Ze/mkuh/e ATTORNEY 1958 v. A. LEHMKUHLE ETAL 2,823,505

AUTOMATIC BAG SELECTOR AND OPENER Filed April 11, 1955 2 Sheets-Sheet 2 INVENTORS' A /b/7ara 6. 0/05 AUTOMATIC BAG SELECTOR AND OPENER Virgil A. Lehmkuhle and Richard G. Oros, Grand Rapids, Mich.

Application April 11, 1955, Serial No. 500,464

9 Claims. (Cl. 53--386) This invention relates to a vacuum operated, automatic machine for selecting and opening collapsed bags from a stack, one at a time.

While various types of mechanisms have been known and used having the purpose of selecting bags one at a time from a bulk quantity of bags, this invention provides a machine which is an appreciable improvement both structurally and functionally over heretofore existing equipment.

This invention provides a fully automatic machine of simple design. The operator does not have to perform any operation other than to remove the bag in order to trigger the machines cycle of operation. The machine is greatly simplified by the complete elimination of valves. This reduces the cost of the equipment and decreases the likelihood of operational failure.

This invention provides a machine not only capable of selecting bags, one at a time, but of positively opening each bag. This latter operation is as important as the selection of the individual bags because of the difficulty so frequently experienced in manually opening bags which have been tightly pressed together.

Having selected, lifted and opened a bag, it will hold it in a convenient position for the operator to grasp. It will continue to do this until the operator is ready to remove the bag. The machine requires only a small amount of vacuum and, therefore, does not require large air pump facilities for efficient operation.

With these objects and advantages in mind, the construction and operation of this invention will be readily understood by those acquainted with equipment of this type upon reading the following specification and the accompanying drawings.

in the drawings:

Fig. 1 is a front elevation view of our invention.

Fig. 2 is an end elevation view of our invention.

Fig. 3 is a rear elevation view of our invention.

Fig. 4 is'a sectional elevation view taken along the plane IV-IV of Fig. 2.

Fig. 5 is a sectional elevation view taken along the plane VV of Fig. 2.

Fig. 6 is a rear view of the inside surface of the rotatable front cover.

Fig. 7 is a front view of the rear housing for our invention.

Fig. 8 is a sectional elevation view taken along the plane VIlIVIII of Fig. 1.

Fig. 9 is a sectional elevation view taken along the plane IX-IX of Fig. 1.

Fig. 10 is a sectional view taken along the plane X-X of Fig. 9.

Fig. 11 is a sectional view taken along the plane XIXI of Fig. 10.

Fig. 12 is an oblique view of a stator vane for our invention.

Fig. 13 is a view of the mounting bushing-for the tubular'arm. p v

United States Patent "ice Fig. 14 is a fragmentary view of the end of the opener arm received into the bushing shown in Fig. 13. v

Fig. 15 is a fragmentary bottom view of the bag lifting tube and its related housing.

Fig. 16 is a fragmentary front view of our invention in advanced or raised position.

In executing the objects and purposes of this inven' tion, we have provided a machine having a cup-shaped, stationary housing. Within this housing is a stator having a pair of diametrically positioned vanes. Vacuum is introduced to the housing and passes through the center of the stator. Enclosing the front end of the housing is a rotatable cover having a pair of fixedvanes extending into the interior of the cup portion of the rear housing and designed to co-operate with the vanes of the stator. Means are provided for introducing the vacuum to the chambers created by the co-operation of the vanes on the stator and on the rotatable cover. Also provided is a tubular plunger designed to grip the bags by suction. The weight of the plunger is such that when the bag has been gripped, the suction will lift I both the plunger and the bag.

A secondary opening is provided about the plunger, which opening is connected to the vacuum source operating the machine. When the plunger is fully withdrawn within the housing, the bag closes the secondary opening, thereby causing the vacuum to operate on the vanes. This initiates rotation of the cover. As the cover is rotated, the bag is carried past the bag opening arm. This arm, by means of a lever, is then caused to move with the rotatable cover. The initial pivotal movement of the opening arm introduces the vacuum to the interior of the arm and by means of an opening adjacent the bag, the bag is pulled open. The pivotal point of the arm and the center of rotation of the cover are offset, causing the arm to recede from the cover. This separation of the arm and cover pulls the bag open. A stop is provided when the bag has been raised and opened to the desired position.

Having reached this stop, the machine will remain stationary until the bag is removed. Removal of the bag permits air to be reintroduced into the interior'of the machine, reducing the vacuum. The machine thereupon will return to its normal position to select another bag.

Referring specifically to the drawings, the numeral 10 indicates a generally U-shaped standard (Figs. 1, 2 and 3). Mounted to and depending from the top of the standard is a generally cup-shaped housing 11. Extending from the upper portion of the housing is a boss which is mounted snugly against the standard 10 by bolts 101. An air tight seal is assured by the use of the gasket 102. Within the boss 100 is a vacuum chamber 103 communicating with the vacuum conduit 13 (Figs. '9, 10 and 11). The vacuum chamber 103 communicates with a channel 12 extending to the center of the housing (Figs. 9 and 10). The conduit 13 is connected to a suitable source of vacuum such as the intake portof an air pump.

The vacuum chamber 103 is traversed by a bushing 14 (Figs. 10 and 11). The bushing 14 is substantially smaller than the vacuum chamber 103, thereby creating an air passageway about the bushing. This permits the vacuum to be created in the channel 12. The bushing has an aperture 15 on one side. The bushing provides a support and pivotal mount for the tubular, swinging arm 16. The end of the tubular arm inserted into the bushing 14 is closed-except for aside port 17. When' the arm is in its inoperative or down position (Fig. 11) the side port 17 is misaligned with the aperture ,15 in:

-' the bushing 14. The aperture 15 and the side port 17 are=so positioned, however, that only a short are of pivotal movement in an upward direction is. required to align them.

The tubular arm 16 is generally U-shaped and extends down, around and under the-housing 12.. Its lower end extends beyond-the front face of the housing andis turned upwardly toward the hereinafter described plunger. The end 18 is open. The purpose'of this construction will be described more fully under Operation.

The vacuum conduit 12- terminates in a concentric, axially extending opening 20 through the rear wall of thehousing 1.1 (Fig. 9). The opening 20 is closed by a detachable gasket cap 19. The intake conduit 13, the vacuum chamber 103 and the vacuum conduit 12, collectively, constitute a single conduit by which air is exhausted'from the interior-of the machine.

The housing 11 has a central chamberll. Integral with the-housing 11 and concentric with the central chamber 21 is an-annular stator hub 22. The length of the stator hub 22 is equal to the depth of the central chamber. The stator hub 22 has a pair of diametrically spaced slots 104 adapted to receive the stator vanes 32 (Fig. The hub has a plurality of air holes 26 passing therethrough. The air holes 26 communicate with the opening 26. A

A central opening 24 extends through the stator 22 (Fig. 7). fress fitted into the opening 24 are a pair of tandemlyarranged bearings 25 (Fig. 9). Press-fitted through the bearings 25 is a shaft 27 flanged at its forward end. Theflange seats in a suitable pocket in the front end of the hub 22. The forward end of the shaft 27 has an externally threaded stud 30. The rear end ofthe opening 24 is closed by a plate 28 secured to the shaft 27 by a screw 29. This construction makes the shaft 27 freely rotatable within the hub 22. It will be recognized that various types of bearings may be used for the bearings 25 such as needle or roller bearings.

The interior surface of the outer wall of the housing 11 has a pair of diametrically spaced slots 31 aligned with theslots 194 of the hub 22 (Fig. 7). The slots 31 receivc, the opposite ends of the stator vanes 32. The front face of the housingalso has a groove 33 designed to co-operate with the cover 40 for preventing air leak between the housing and the cover.

The stator vanes 32 are wedge-shaped (Fig. 12) and each has an opening for a screw for securing them to the housing 11. The vane attaching screws engage the threaded openings 34 in the housing 11 (Fig. 7).

The open forward end of the housing 11 is closed by a-rotatable cover 40. The cover 40 has a central, threaded opening 41 (Fig. 6) designed to receive the threaded stud 30 (Fig. 9). Adjacent the opening 41are a pair of arcuate passageways 42 and 42a, radially spaced from. the center of the cover to align with the air passageways 26 extending through the hub 22. Because of the multiplicity of the air passageways 26, one or more of them will always be aligned with each of the arcuate passageways 42 and 42a, irrespective of the length of the arc of rotation of the cover 40. Extendingfrom the upper arouate passageway 42 is a conduit- 43 opening through the interior face of the cover 40. Extending from the lower arcuate passageway 42a is a second conduit 43a opening through the interior face of the cover. The openings for the passageways 43 and 43a are generally diametrically positioned with respect to-each other.

Adjacent each of the passageways 43 and 43a is a rearwardly extending vane 44 (-Figs. 6 and 8). The vanes 44. are integral with the cover and are designed to seat within the interior chamber 21 of the housing and to approach the side walls of the interior chamber 2]? as closely as possible without binding. The radial,

inner ends of the vanes,.44 are designed; tojustcleargthey hub Theseclearances with the hub and with the walls of the housing are such as to prevent any substantial leakage-of air at either of these points but great enough to eliminate possible binding between the parts.

The vanes 44, together with the vanes 32, form four chambers within the housing (Fig. 5). These chambers constitute the vacuum chambers 45 and the pressure chambers 46 (Fig. 5). The conduits 43 and 43:: open into the vacuum chambers 45. The pressure chambers 46 are each individually vented to the atmosphere through the cover 40 by meansof the holes 47. The purpose of this arrangement will appear more fully hereinafter.

Extending forwardly frorn'the front or exterior face of thecover 40" is a hollow casing 50. The vertical center line of the hollow casing is centered about a diameter of the cover 40; The lower portion of the casing 50 extends substantially below the cover 40. The interior opening 51 within the hollow casing 50 is circular and receives the tubular piston or plunger 52 (Fig. 4).

Projecting into the interior opening 51 of the casing SO-area pair of spaced, annular baffles and 36 (Fig. 4). The lower bafile 35 is at the lower end of'the casing- 50.- The upper baffle 36 is spaced substantially above the lower one. The central openings in the baflies 35-and36-slidably receive the tubular plunger 52. Both of the baffles have a pair of small orifice or air passages -37 through them (Fig. 15). The orifices 37 provide the secondary air passages which bypass the plunger.

The plunger 52, adjacent its upper end, has side slots 38; It also has-stop pins 39 designed to limit downward or extending travel of the plunger. The lower end of the plunger has a cross bar 48 designed to prevent the bags being drawn into the end of the plunger (Fig. 15

A plurality of openings 49 through the cover providing communication between the opening 51 in the casing and the-arcuate passageways 42 and 42a (Figs- 4 and 6). Thus, air may be exhausted from the interior of the casing 50. Since the tubular plunger 52 is open at both ends, air may be drawn into the interior opening 51 of the casing 50 through the plunger.

The upper end of the casing 50 is closed by a cover 54and gasket 55. The cover 54 is detachably secured by screws. 56. Extending through the cover 54 is a vertically adjustable stop 57 for the plunger 52'. The stop-is locked by means of the nut 58.

Mounted on the exterior of the cover 40 is a counterweight 60. T he counterweight functions to balance the cover whereby it maybe freely rotated by the vacuum without the necessity of overcoming the resistance which wouldbe created by eccentric loading of the cover.

Extending from the lower end of the rearward face of the housing 11 is a rod 70 (Figs. 2 and 3). The rod 70 serves as a stop against the downward movement of the tubulararm 16. Projecting rearwardly from a boss 62 on the tubular casing 50 is a second rod 71. The sec- 0nd rod.7ll is offset-and its length is such that it passes beyond the rearward extremity of the tubular arm 16. As the cover 40 is rotated, the arm 71 is carried with it.

After a predetermined arc of travel, the rod 71 contacts the swinging arm 16 and thereafter carries the sw1ngarm'16 up with it. A stop collar 63 is provided on the swinging arm 16. Contact between the stop collar 63 and the rod 71 limits the upward rotation of the cover 40 (Fig. 16). The stop collar 63 is adjustable along the-swinging arm 16.

The length of the arc of movement of the cover 40 before movement of the swinging arm is initiated may be ad usted by rotating the rod 71 after loosening the nut 64.

The rod 70 is also offset so that by rotation the downward limit of travel of the swinging arm 16 may be adusted- Adjustment may be made upon loosening the nut 65 (Fig. 2).

Operation The machine, as it appears in Fig. 1, is in its at rest or inoperat ve. position. A stack of bags are placedbeneath the plunger 52. Normally, the bags are placed in a box or other container so the plunger, when it drops to its bottom position, may reach to the bottom of the stack of bags. In order to slip the bags under the plunger, the plunger is raised by telescoping it into the casing 50. This is easily done since the plunger may reciprocate freely within the channel.

After the bags have been placed with the open end of the bag extending to the right, as the machine appears in Fig. 1, and the open end of the bag closely adjacent the plunger 52, the plunger is dropped on the bags. A vacuum is then created in the machine through the conduit 13 by any suitable means such as an air pump. With the machine in'this position, the apertures 15 and 17 at the upper end of the swinging arm 16 are misaligned as they appear in Fig. 11. Thus, air will not be drawn into the vacuum chamber 103 through the tubular arm 16. As a result, air is exhausted from the central opening 20 and thus through the center of the hub 22 (Fig. 9). Some air will be withdrawn from the vacuum chambers 45 but this will not be enough to cause the rotatable cover 40 to move since a sufficient supply of air will pass into the interior of the machine through the orifices 37 in the bafiies 35 and 36 of the casing 50 (Fig. 4). Air entering through the orifices 37 passes through the openings 49 and the arcuate passageways 42 and 42a.

At the same time, air will be withdrawn from the interior opening 51 of the casing 50 through the openings 49. This will immediately draw the bag tightly against the open, lower end of the plunger 52, shutting oif this supply of air. As a result of this, the plunger 52 will be lifted due to the upwardly directed vector of force resulting from the lowering of pressure within the plunger and the atmospheric pressure bearing against that portion of the bag covering the lower end of the plunger 52. The plunger 52 will rise, separating the bag from the pile.

The plunger will continue to rise until it is entirely withdrawn into the casing 50. At this point, the bag will seat across the orifices 37 in the lower baffle 35, closing them. With the supply of air to the interior of the machine through both the plunger 52 and the orifices 37 shut off, a vacuum Will rapidly be created within the vacuum chambers 45 by the air being exhausted through the conduits 43 and 43a. Since the pressure chambers 46 are both open to the atmosphere through the ports 47, a pressure differential will result between the opposite surfaces of the vanes 44. This will force the vanes 44 away from the ports '47. Since the vanes 44 are affixed to the cover 40, the cover and its related structure will be rotated.

In the initial portion of its rotation, the bag will be carried between the casing 50 and the forward, lower end of the tubular arm 16. When the end of the bag, designed to be opened, has just passed the open end 18 of the arm 16, contact between the rod 71 and the swinging arm 16 will initiate movement of the arm 16 along with the rotatable head 40. Shortly thereafter, the apertures 15. and 17 (Fig. 11) will become aligned and air will be exhausted from the tubular arm 16. One side of the bagwill then be drawn tightly against the open end 18 of the arm, pulling the sides of the bag apart.

The head 40 will continue to rotate upwardly in the direction of the arrow in Fig. 1 until its upward progress is prevented by contact between the rod 71 and the stop collar 63 (Fig. 16). During this upward movement, the lower end of the tubular arm 16 will separate from the casing 50, pulling the sides of the bag further apart. The amount the bag is opened by the upward movement of the machine will be determined by the length of the arc of rotation of the rotatable cover 40, since the greater the rotation the greater will be the separation between the arm 16 and the casing 50 due to the'eccentricity of their centers of rotation.

' The machine, having reached the upper limit of its travel, will remain stationary, holding the bag in position by reason of the vacuum resulting from the bag pre 6 venting the entrance of air into the machine. The machine will continue to hold the bag as long as desired by the operator. When the operator is ready for the bag, he removes it merely by pulling it away from the vacuum.

As soon as this happens, air will once more enter in substantial quantities through the casing 50. The slight eccentricity in weighting of the cover 40 will cause it to return to its normal position. As it does so, the plunger 52 will extend from the casing 50. At the same time, the arm 16 will drop back to its initial position as rapidly as the stop rod 71 permits. Thus, the plunger 52 will, by gravity, drop upon the top bag of the pile beneath. As soon as this happens, the supply of air through the plunger 52 is blocked and the cycle of selecting, lifting and opening another bag will be repeated.

The stop rod 70 prevents the arm 16 from swinging too farin its return movement. By preventing the arm 16 from swinging all the way back with the rod 71, a certain amount of upward movement of the cover 40 and casing 50 is permitted before movement of the arm is initiated. This is important since it permits the bag to be placed over the open end 18 of the arm before the armstarts to move and before the vacuum is applied. If the vacuum is applied to the arm 16 before the bag is in position, the edge of the bag will be drawn into the open end 18 and only a partial blockade of the air entering this opening will be created.

The structure of this machine eliminates all conventional valves. The only control of the movement of air through the machine is effected either by the relative alignment of the apertures 15 and 17 (Fig. 11) or by the bag itself as it closes the three different air inlets, that being the end of the plunger 52, the orifices 37 and the open end 18 of the arm 16.

The machine is operated by a careful balance between the volume of air being exhausted through the conduit 13 and the volume of air being admitted from all sources. The volume of air being admitted when the plunger 52 and orifices 37 are both open is so great that no effective pressure differential occurs within the machine. When, however, the end of the plunger is closed, this balance is disturbed, resulting in the retraction of the plunger due to an increase in pressure differential throughout the machine. The volume of air admitted by the orifices 37 is such that this differential will lift the plunger but will be insufiicient to rotate the cover 40.

When, however, the orifices 37 are closed, the differential within the machine increases substantially. This increase overcomes the balance of forces keeping the cover in equilibrium. The cover then starts to rotate. The volume of air momentarily admitted by the open end 18 of the arm 16 is not only not great enough to destroy the pressure differential rotating the cover 40 but its duration is so short that, at most, it might cause slight hesitation in the covers rotation.

The retraction of the plunger 52 into the casing 50 also reduces the forces acting against rotation of the cover 40. Thus, when the orifices 37 are finally closed, the force required to upset the equilibrium of the cover is substantially less than that which is necessary when the plunger is extended.

The elimination of conventional valve structure simplifies the machine and greatly reduces the possibility of operational failure. It also reduces the initial cost of the machine because such valves are normally expensive components.

The construction of the machine makes it wholly unnecessary for the operator to trip any valves or do anything to the machine to cause it to repeat its cycle of operation. Thus, it is easier to train an operator in its proper operation and requires less of the operators time. This materially speeds up the whole operation.

While we have described a preferred embodiment of this invention, it will be recognized that various modifications may be made. Each of these modifications is to '7 be--considere d as included in the hereinafter appended; cIaimsunIess these, claims expressly state otherwise;

We claim:

1. In a bag selecting machine, the combination comprising: a hollow housing having a stationary member and a rotatable member; said rotatable member being biased toward bag receiving position; a stationary vane within said housing; a rotatable vane Within said housing adapted to cooperate with said stationary vane to form a vacuum chamber and a pressure chamber; said rotatable vane being fixedly secured to said rotatable member; a tubular casing on said rotatable member; a tubular plunger slidably received in said casing; an air passage in said casing adjacent said plunger; conduit means for simultaneously exhausting air from said vacuum chamber of said housing, together with air entering through said plunger and through said airrpassage; the size of said air passage being such that whenthe endof said plunger is closed suflicient pressure differential will be created in said casing to raise said plunger but insufiicient to rotate said rotatable vane; said rotatablevane being adapted to move said rotatable member away from said bag receiving position when both the end of said plunger and of said air passage are closed.

2. In a bag selecting machine, the combination comprising: a hollow housing having a stationary member and a rotatable member; said rotatable member being biased toward bag receiving position; stationary vanes within said housing; rotatable vanes within said housing adapted to cooperate with said stationary vanes to form vacuum chambers and pressure chambers; said rotatable vanes being fixedly secured to said rotatable member; a hollow casing on said rotatable member; a tubular plunger slidably received in said casing; an air passage in said casing adjacent said plunger; conduit means for simultaneously exhausting air from the vacuum chambers of said housing, together with air entering through said plunger and through said air passage; the size of said air passage being such that when the end of said plunger is closed sufiicient pressure diiterential will be created in said casing to raise said plunger but insufiicient to rotate said rotatable vanes; said rotatable vanes being adapted to move said rotatable member away from said bag receiving position when both the end of said plunger and of said air passage are closed.

3. In a bag selecting machine, the combination comprising: a hollow housing having a stationary member and a rotatable member; said rotatable member being biased toward bag receiving position; a tubular casing on said rotatable member; a tubular plunger slidably received in said casing; an air passage in said casing adjacent said plunger; conduit means for simultaneously exhausting air from the interior of said housing, together with air entering through said plunger and through said air passage; air pressure difierential operated means within said housing afiixed to said rotatable membeiy said means being adapted to rotate said cover when the air pressure differential within said housing exceeds a predetermined amount; the size of said air passage being such that when the end of saidplunger is closed sufficient pressure differential will be created in said casing to raise said plunger but insuflicient to operate said means; said means being adapted to move said rotatable member away from said bag receiving position when both the end of said plunger and of said air passage are closed.

4. In a bag selecting machine, the combination comprising: a hollow housing having a stationary member and'a rotatable member; said rotatable member being biased toward bag receiving position; stationary vanes withinsaid housing; rotatable vanes within said housing adapted to cooperate'with saidstationary vanes to form vacuum chambers and pressure chambers; said rotatable vanes being fixedly secured to said rotatable member; a tubular casing on said rotatable member; a tubular plunger slidably received in said casing; an air passage in '8 said casing adjacent said plunger; conduit means for simultaneously exhausting air from the vacuum chambers of said housing, together with air entering through said plunger and through said air passage; the sizeof said air passage being such that when the end of said plunger is closed sufficient pressure diflerential will be createdin said casing to raise said plunger but insufficient to rotate said rotatable vanes; said rotatable vanes being adapted to move said rotatable member away from said bag receiving position when both the end of said plunger and of said air passage are closed; a tubular arm pivotally secured to said housing; one end of said arm being radially spaced from said casing as said rotatable member rotates; said arm having an air intake port aligned with the end of said plunger as said rotatable member rotates; a lost motion connection adapted to move said arm with said rotatable member after said plunger and said intake port have become axially aligned; a normally closed air exhaust port in the other end of said arm, said port being movable into communication with said conduit means after-said plunger and air intake port are aligned.

5. In a bag selecting machine, the combination comprising: a hollow housing having a stationary member and a rotatable member; said rotatable member being biased toward bag receiving position; stationary vanes within said housing; rotatable vanestwithin said housing and cooperating with said stationary vanesto form vacuum chambers and pressure chambers; said rotatable vanes being fixedly secured to said rotatable member; a tubular casing on said rotatable member; a tubular plunger slidably received in said casing; an air passage in said casing adjacent said plunger; conduit means for simultaneously exhausting air from the vacuum chambers of said housing, together with air entering through said plunger and through said air passage; the size ofsaid air passage being such that when the end of said plunger is closed sufiicient pressure differential will be created in said casing to raise said plunger but insufficient to rotate said rotatable vanes; said rotatable vanes being adapted to move said rotatable member away from said bag receiving position when both the end of said. plunger and of said air passage are closed; a tubular arm pivotally secured to said housing; one endof said arm being radially spaced .from said casing as said rotatable member rotates; said arm having an air intake port aligned with the end of said plunger as said rotatable member rotates; a lost motion connection adapted to move said arm with said rotatable member after: said plunger and said intake port have become axially aligned; a normally closed air .exhaust port in the other end of said arm, said port being movable into communication with said conduit means after said plunger and air intake port are aligned; said point of pivotal mounting of said swinging arm being remote and spaced further from the end of said plunger than said axis of rotation of said rotatable member whereby said arm and casing diverge as said rotatable member swings upwardly.

6. In a bag selecting machine, the combination. comprising: a hollow housing having a stationary member and a rotatable member; said rotatable member being biased toward bag receiving position; a stationary vane within said housing; a rotatable vane within said housing adapted to cooperate with said stationary vane to form a vacuum chamber and a pressure chamber; said rotatable vane being fixedly secured to said rotatable member; a tubular casing on said rotatable member; a tubular plunger slidably received in said casing; an air passage in said casing adjacent said plunger; conduit means for simultaneously exhausting air from the vacuum chamber of said housing, together with air entering through said plunger and through said air passage;'the size: of said air passage being such that the end of said plunger is closed sufficient pressure differential will be created in said casing to raise said plunger but insufiicient to rotate said rotatable vane; said rotatable vane beingadapted to move 9 4 said rotatable member away from said bag receiving position when both the end of said plunger and of said air passage are closed; a tubular arm pivotally secured to said housing; one end of said arm being radially spaced from said casing as said rotatable member rotates; said arm having an air intake port aligned with the end of said plunger as said rotatable member rotates; a lost motion connected adapted to move said arm with said rotatable member after said plunger and said intake port have become axially aligned; a normally closed air exhaust port in the other end of said arm, said port being movable into communication with said conduit means after said plunger and air intake port are aligned.

7. In a bag selecting machine, the combination comprising: a hollow housing having a stationary member and a rotatable member; said rotatable member being biased toward bag receiving position; a tubular casing on said rotatable member; a tubular plunger slidably received in said casing; an air passage in said casing adjacent said plunger; conduit means for simultaneously exhausting air from the interior of said housing, together with air entering through said plunger and through said air passage; air pressure differential operated means within said housing afiixed to said rotatable member, said means being adapted to rotate said cover when the air pressure differential within said housing exceeds a predetermined amount; the size of said air passage being such that when the end of said plunger is closed sufiicient pressure difierential will be created in said casing to raise said plunger but insufficient to operate said means; said means being adapted to move said rotatable member away from said bag receiving position when both the end of said plunger and of said air passage are closed; a tubular arm pivotally secured to said housing; one end of said arm being radially spaced from said casing as said rotatable member rotates; said arm having an air intake port aligned with the end of said plunger as said rotatable member rotates; a lost motion connection adapted to move said arm with said rotatable member after said plunger and said intake port have become axially aligned; a normally closed air exhaust port in the other end of said arm, said port being movable into communication with said conduit means after said plunger and air intake port are aligned.

8. In a bag selecting machine adapted to be used with a source of vacuum, the combination comprising: a housing having a stationary member and a movable member; said movable member being biased to bag receiving position; a tubular casing 011 said movable member; a tubular plunger slidably received in said casing; an air passage in said casing adjacent said plunger; a vacuum operated motor for moving said movable member away from said bag receiving position when sufficient vacuum is applied to it; conduit means for simultaneously exhausting air from said motor together with air entering through said plunger and said air passage; the size of said air passage being such that when the end of said plunger is closed, sutficient pressure difierential will be created in said casing to raise said plunger but insufficient to move said motor; said motor being adapted to move said movable member away from said bag receiving position when the ends of both said plunger and said air passage are closed.

9. In a bag selecting machine adapted to be used with a source of vacuum, the combination comprising: a housing having a stationary member and a movable member; said movable member being biased to bag receiving position; a tubular casing on said movable member; a tubular plunger slidably received in said casing; an air passage in said casing adjacent said plunger; a vacuum operated motor for moving said movable member away from said bag receiving position when sufiicient vacuum is applied to it; conduit means for simultaneously exhausting air from said motor together with air entering through said plunger and said air passage; the size of said air passage being such that when the end of said plunger is closed, sutficient pressure differential will be created in said casing to raise said plunger but insufiicient to move said motor; said motor being adapted to move said movable member away from said bag receiving position when the ends of both said plunger and said air passage are closed; a tubular arm movably connected to said housing for travel with said movable member as said movable member moves away from said bag receiving position; said arm being adapted to recede radially from said movable member as said movable member moves away from said bag receiving position; said arm having an air intake port adapted to become aligned with the end of said plunger as said movable member moves; means to exhaust air from said tubular arm after said air intake port and plunger have become aligned.

References Cited in the file of this patent UNITED STATES PATENTS 2,051,483 Jones Aug. 18, 1936 2,341,521 Baker et a]. Feb. 15, 1944 2,563,450 Battey Aug. 7, 1950 

